First, you need to do well in High School, to get admitted to university for a "Bachelor's Degree" (often referred to as an "undergraduate degree"). This is typically a 4-year program. The good news there is you can major in ANYTHING you like. For example, I have a Bachelor's of Science in Marine Science & Biology. Some people will tell you that political science or English (there is a lot of reading and writing in law school!) will give you an edge in law school, but I strongly believe that you should study what you love and get the best grades possible. Hate to say it, but grades matter a lot. ( I respectfully disagree with Valerie that it takes 2 years to prep for the LSAT and that the LSAT prep is any part of a Bachelor's curriculum. You can read a book on the LSAT and/or take a prep class for a few weeks before the exam.)
You need good grades with your Bachelor's Degree and a strong LSAT score. The LSAT - unlike, say, the SAT - doesn't test your math skills or substantive knowledge but rather the way you think. It has three types of multiple choice questions testing (a) reading comprehension, (b) analytical reasoning, and (c) logical reasoning, along with a writing sample. If you like puzzles and logic games, you might actually enjoy the LSAT questions (but the time pressure is intense). Many companies offer tutoring for the LSAT exam - but you can also studying up on it on your own (that's what I did).
With good grades from University and strong LSAT score, you start applying to law school to earn a Juris Doctorate (JD) degree. One thing that matters a lot to future employment is getting into a so-called a high or top tier law school. Play close attention to the ranking and accreditation of potential law schools, because they are a huge determining factor of future employment. A low ranked law school - or one that looses its accreditation - could leave you burdened with student debt and no likely employment prospects. Law School is typically a 3-year program. Again, getting good grades matters a lot to prospective employers, with students at the top of the class competing (with all the top students at all the top law schools) for jobs after graduation. It it common to have a paid internship the summer before your final year at law school at a law firm -- a so-called "summer associate" position -- to get "real world" experience and to see if the firm is a good fit. Successful summer associates may get early job offers (pending law school graduation and passing the bar exam). The last semester of law school, graduating students who haven't already secured a job trying to get offers for jobs - on top of their studies.
Once you graduate with your JD, most states require you pass an ethics exam (typically "easy" if you've made it through law school), the infamous Bar Exam (hard, I'm not going to lie it was the hardest test ever in my entire life) as well as a "character and fitness" interview with a practicing attorney. Each state has its own standards and requirements for what a passing score is on the Bar Exam and how much the multi-state/multiple choose portion of the exams weighs against the written essay portion of the test.
Once you have all of these steps, you are "admitted to the Bar". Afterwards, most states require you to take "Continuing Legal Education" classes and volunteer at/contribute to legal clinics for the whole time you are a practicing attorney.
My boyfriend is an attorney so I hope I am able to answer your question. First you must go to college for 4 years, and during your last 2 years you will prepare and take the LSAT to get into law school. Law school is 3 more years after college, and then when you graduate you will take the bar exam. After you pass the bar exam you can get a job to become an attorney.
I hope this helps!